CHARGING BY SUPERHEAT
CHECK AIR FLOW
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MAKE SURE FILTERS ARE CLEAN
NO RESTRICTIVE FILTERS IN PLACE
IS THE BLOWER WHEEL CLEAN
IS THE EVAPORATOR COIL CLEAN
MAKE SURE YOU HAVE 400 CFM OF
AIR FLOW PER TON
FIXED ORFICE SYSTEMS
• Connect service gauges to base-valve service
ports .
• Be sure to purge the lines.
• Install thermometer to the suction line and
insulate for an accurate reading
• Refer to the table for proper system Superheat
• Add charge to lower Superheat
• Remove charge to raise Superheat
• Remove gauge lines carefully
SUPERHEAT TABLE
USING SUPERHEAT TABLE
• GET THE OUTSIDE AMBIENT
TEMPERATURE IN THE SHADE OF THE
CONDENSING UNIT
• GET THE RETURN DRY BULB
TEMPERATURE AT THE RETURN AIR GRILL
• INTERSECT THE 2 NUMBERS
• THAT WILL GIVE YOU THE AMOUNT OF
SUPERHEAT YOU NEED
EXAMPLE
• AMBIENT OUTSIDE TEMPERATURE
(IN THE SHADE OF THE
CONDENSOR) IS 95 DEGRESS
• RETURN AIR (DRY BULB) IS 75
DEGREES
• INTERSECT THE 2 NUMBERS AND
YOUR SUPER HEAT WILL BE 5
DEGREES
READING THE SATURATED
EVAPORATER TEMPERTURE
• ON THE LOW SIDE OF YOUR
COMPOUND GAUGES ( BLUE )
• THE OUTSIDE READING IS YOUR
PRESSURE
• THE INSIDE (R 22) IS YOUR
SATURATED EVAPORIZING
TEMPERTURE
INSTALL THERMOMETER
• INSTALL ON THE SUCTION LINE
LARGER LINE )
• INSULATE THE PROBE FOR AN
MORE ACCURATE READING
(
EXAMPLE
• YOUR LOW SIDE PRESSURE IS 75
PSI
• DIRECTLY BELOW THAT NUMBER IS
THE SATURATED EVAPORIZING
TEMPERATURE, WHICH IS 44
DEGREES
• TAKE YOU SUCTION LINE
TEMPERTURE, WHICH IS 65
DEGREE
EXAMPLE
• SUBTRACT THE 2 NUMBERS AND THAT
HOW MUCH SUPEREHEAT YOU HAVE
• 65 - 44 =21 SUPERHEAT
• WE ONLY NEEDED 5 DEGREES
• ADD CHARGE TO LOWER SUPER HEAT
• REMOVE CHARGE TO RAISE SUPERHEAT
CHARGING BY SUBCOOLING
CHECKING SUBCOOLING
Refrigeration liquid is considered subcooled when its
temperature is lower than the saturation temperature
corresponding to its pressure. The degree of subcooling
equals the degrees of temperature decrease below the
saturation temperature at the existing pressure.
CHECKING SUBCOOLING
1. Attach an accurate thermometer or preferably a thermocouple
type temperature tester to the liquid line as it leaves the
condensing unit.
2. Install a high side pressure gauge on the high side (liquid)
service valve at the front of the unit.
3. Record the gauge pressure and the temperature of the line.
4. Convert the liquid line pressure gauge reading to temperature by
finding the gauge reading in the Temperature – Pressure Chart
and reading to the left, find the temperature in F column.
5. The difference between the thermometer reading and pressure to
the temperature conversion is the amount of subcooling.
CHECKING SUBCOOLING
EXAMPLE:
a) Liquid Line Pressure = 260
b) Corresponding Temp. = 120 degrees
c) Thermometer on Liquid line = 109 degrees
To obtain the amount of subcooling subtract 109 degrees from 120 degrees.
The difference is 11 degrees subcooling. The normal subcooling range is 9 -13
Degrees subcooling for heat pumps units , 14 to 18 degrees for straight cool
Units.
any questions?
Thank you!